Melanie "Mel" (Bonnie Langford)
During the Doctor's trial, he presented an example of his adventures, to defend himself against the accusations of the prosecutor, The Valeyard. This introduced Mel, a bright and bubbly keep-fit fanatic, from Pease Pottage, Sussex.
Mel tried, unsuccessfully, to introduce the Doctor to a regime of exercise and carrot juice. After the trial, she was still travelling with the Doctor, when an attack by a renegade Time Lord, the Rani, caused him to regenerate.
Mel elected to leave the Doctor after an adventure on the ice planet Svartos, and joined forces with the roguish Sabalom Glitz, perhaps hoping to reform him.